British politics has drifted in the opposite direction, visible most notably in the government’s Brexit White Paper rejecting FoM and promising quantitative restrictions on EU citizens moving to the UK. Only the Liberal Democrats and the Greens say they want to keep FoM, whereas Labour is divided. After initially defending the economic and social benefits of immigration, the Labour leader appears ready to abandon it.

Those who press the case for dropping it put forward a simple justification: FoM stands for an open-door immigration policy, and restricting this was one of most important motivations for a majority of Leave voters. If framed in this way, any prize is worth paying for “reasserting control” over the borders.

However, equating FoM with unlimited immigration is flawed, whilst we argue it should be framed as a right, insurance, and a symbolic bond.

FoM is not an immigration policy but a legal right, enshrined in the EU treaties and elaborated in the Citizenship Directive, to work and study in another EU country. It applies to all EU citizens as a result of their country’s membership of the EU. An estimated 1.2 million British citizens have used the many opportunities it brings to work, study and retire in other EU countries, especially Spain, Ireland, France and Germany.

In this sense, freedom of movement does not discriminate against non-EU migrants, as is sometimes claimed, because non-EU countries do not guarantee British citizens reciprocal rights of this kind. It would therefore be consistent to defend FoM, but argue for tighter controls on immigration from outside the EU.

It would also be wrong to claim that FoM creates unlimited immigration. It does not extend to non-EU citizens as our colleague Steve Peers pointed out. This matters because the overwhelming part of net-inflows over the last ten years has been from outside the EU. Even if net migration from the EU had been zero, the government would have still missed its 100,000 or less net migration target for most years since 2010 when the policy was adopted.

FoM is also an insurance policy in case of an outside shock affecting Britain, an unexpected closing down of non-EU destinations or a divergence in living standards with the rest of the EU. While it may appear far-fetched today to envisage a thriving Eurozone and a struggling British economy, we do not need to go far back into British and European history to see that push and pull factors of intra-European migration can and do change.

The decision to either uphold or abandon FoM will be highly symbolic in the message the country sends to other Europeans. It will be followed closely by the 3 million EU citizens living in its midst, working in the NHS, in schools and contributing in various ways to economic and social life. Many EU citizen did not perceive themselves to be migrants in the conventional sense who needed to leave behind their national identity.

Today, many feel unsettled and some betrayed by a country in which they have built their lives and that of their families. Outside the UK, Brexit is rarely attributed to concerns over democratic self-determination, but often portrayed as being motivated by anti-immigrant sentiments. The stance British politicians take on FoM will either reinforce or mitigate that impression. It will be a litmus test of British attitudes to fellow Europeans and is likely to shape the political and cultural relationship for years to come.

Those who have defended FoM have proposed sensible measures to mitigate some of the pressures created by the inflows – for instance, by providing extra funding to schools and hospitals in particular areas, or strengthening workers’ rights. In contrast, little thought has been given to enable and encourage more British citizens to make full use of their own rights and help ease obstacles in other European countries.

This could include measures to better resource and make compulsory the teaching of a European Language up to GCSE level, improving vocational training, providing better guidance on how to seek a job abroad and working with other European countries to remove obstacles to accessing continental European markets, perhaps by strengthening the mutual recognition of qualifications.

In the end though, these policies can only be implemented if freedom of movement is not predominantly seen as a burden and political liability, but understood as an opportunity, insurance and bond.

By Professor Christoph Meyer at King’s College London and Professor Eiko Thielemann London School of Economics and Political Science.

Disclaimer: The views expressed in this analysis post are those of the authors and not necessarily those of the UK in a Changing Europe initiative.